1. Field of the Invention
This invention relates to material stability testing and in particular to testing and monitoring the stability of samples such as chemicals, foods or food additives, biocides, agrochemicals and especially pharmaceuticals.
2. Discussion of the Background
During product development an integral part of the physiochemical characterisation of substances such as food additives, drugs or other materials development is the collection of large amounts of data on the stability of the material being developed. Typical examples of stability tests include those testing the effects of relative humidity and/or a temperature on a product. Such testing is especially relevant in the pharmaceutical industry where huge numbers of different compounds must be tested during all stages of product development. Drugs in early development are usually only available in small amounts and are expensive, limiting the quantities that can be used for stability studies.
Conventional methods for testing humidity and/or temperature include the use of relatively large humidity cabinets or rooms. Such methods are very expensive in a number of aspects. The cost of setting up tests using such systems can run into hundreds of thousands of euro for the initial capital outlay and maintenance costs. This can represent significant costs for many small to medium sized firms.
Some conventional stability testing methods involve placing materials in open petri dishes and placing the petri dishes in humidity cabinets or rooms. In this way a number of samples are tested together under the same conditions. However, when problems occur with the equipment the whole batch result is nullified. Also, dealing with open petri dishes is not suitable for toxic substances. Furthermore, the set humidity in the cabinet is disturbed upon opening of the cabinet in order to study the materials being tested or when inserting or removing individual samples.
Other methods, such as placing the samples in glass cabinets or jars containing saturated salts which generate a humid atmosphere may take up to two days to set up a range of samples under different conditions. Also the climate conditions within the cabinet or jar cannot be checked without adversely affecting the test. Setting up a range of saturated salts and the range of samples to cover various tests is slow and cumbersome using this type of standard laboratory equipment. Because of this, the drug developer will usually only set up the most essential and significant test limiting the amount of information that could be generated in early development.
Another problem often encountered is a degradant showing up in the stability trials after key milestones of product development have been reached, such as clinical studies. The changing to a more stable drug formulation at any of these stages is very costly and critical in the current age of quickness of the market.
Another type of material stability test kit and method is described in our previous patent application PCT/IE00/00135 (Publication No. WO 01/31316).
It is an object of the present invention to provide an improved material stability test system which overcomes the aforementioned problems.